Add support for list default value

lib/kredis/attributes.rb

@@ -42,8 +42,8 @@ def kredis_json(name, key: nil, config: :shared, after_change: nil, expires_in:
       kredis_connection_with __method__, name, key, config: config, after_change: after_change, expires_in: expires_in
     end
 
-    def kredis_list(name, key: nil, typed: :string, config: :shared, after_change: nil)
-      kredis_connection_with __method__, name, key, typed: typed, config: config, after_change: after_change
+    def kredis_list(name, key: nil, typed: :string, config: :shared, after_change: nil, default: nil)
+      kredis_connection_with __method__, name, key, typed: typed, config: config, after_change: after_change, default: default
     end
 
     def kredis_unique_list(name, limit: nil, key: nil, typed: :string, config: :shared, after_change: nil)

lib/kredis/types.rb

@@ -59,8 +59,8 @@ def hash(key, typed: :string, config: :shared, after_change: nil)
     type_from(Hash, config, key, after_change: after_change, typed: typed)
   end
 
-  def list(key, typed: :string, config: :shared, after_change: nil)
-    type_from(List, config, key, after_change: after_change, typed: typed)
+  def list(key, typed: :string, config: :shared, after_change: nil, default: nil)
+    type_from(List, config, key, after_change: after_change, typed: typed, default: default)
   end
 
   def unique_list(key, typed: :string, limit: nil, config: :shared, after_change: nil)

lib/kredis/types/list.rb

@@ -1,10 +1,17 @@
 class Kredis::Types::List < Kredis::Types::Proxying
   proxying :lrange, :lrem, :lpush, :rpush, :exists?, :del
 
-  attr_accessor :typed
+  attr_accessor :typed, :default
 
   def elements
-    strings_to_types(lrange(0, -1) || [], typed)
+    raw_value = lrange(0, -1)
+
+    if raw_value.empty?
+      raw_value = list_default_evaluated
+      append(raw_value)
+    end
+
+    strings_to_types(raw_value, typed)
   end
   alias to_a elements
 
@@ -24,4 +31,10 @@ def append(*elements)
   def clear
     del
   end
+
+  private
+
+  def list_default_evaluated
+    default.is_a?(Proc) ? default.call(self) : default
+  end
 end

test/types/list_test.rb

@@ -2,7 +2,11 @@
 require "active_support/core_ext/integer"
 
 class ListTest < ActiveSupport::TestCase
-  setup { @list = Kredis.list "mylist" }
+  setup { @list = Kredis.list "mylist", default: ->(_) { %w[ 1 2 3 ] } }
+
+  test "default" do
+    assert_equal %w[ 1 2 3 ], @list.elements
+  end
 
   test "append" do
     @list.append(%w[ 1 2 3 ])
@@ -38,7 +42,7 @@ class ListTest < ActiveSupport::TestCase
   test "clear" do
     @list.append(%w[ 1 2 3 4 ])
     @list.clear
-    assert_equal [], @list.elements
+    assert_equal %w[ 1 2 3 ], @list.elements
   end
 
   test "typed as datetime" do